The present invention relates to cutting tools or drill bits, and more particularly, to cutting tools which are used in hammering, percussive, or rotary boring or drilling applications in concrete, aggregate, masonry or the like material.
When drilling concrete, aggregate or the like materials, generally three different types of cutting tools or bits are used. These bits can be defined as hammer bits, percussive bits, and rotary masonry bits. In a true hammer bit, the bit is placed into a driver which includes a hammer which is sequentially and repetitiously moved toward and away from the bit. This hammering action hammers the bit. While the bit is being hammered, the bit continues to either passively or actively rotate. Thus, this type of cutting would be synonymous with using a chisel and hitting it with a hammer. Also, the driver may include a rotational feature where the bit is hammered and actively rotated.
In percussive drilling, the drive includes a chuck which is associated with stepping cam surfaces on gears which are rotated and, at the same time, moved up and down within the driver. Thus, the entire chuck mechanism rotates and moves up and down during the cutting process.
A rotary masonry bit is positioned into a driver which provides only a rotary movement. Thus, the rotary masonry bit does not move up and down and just rotates to cut at the concrete or aggregate.
Cutting tools in these three fields require different parameters for each type of application. In hammer and percussive bits, which utilize a chiseling action, the tip cutting angle, which provides tip strength, debris elimination and a cutting or rake face are a primary concern. Likewise, in rotary masonry drilling, which uses purely rotary movement, the cutting or rake face, debris clean out and cutting angle are also of primary importance. However, all of these elements are interrelated to provide an optimum cutting tool or drill bit to drill concrete, aggregate and the like materials.
Existing hammer and percussive cutting tools ordinarily include carbide insert tips with cutting edges which have large obtuse included angles as well as a negative rake face at large acute angles. Thus, the tip has been utilized to chisel and rotate to drill or bore into the concrete material. The rotary masonry bits ordinarily use a rake face on the bit so that when it is rotated, it will bore through the concrete material.
Further, when the carbide tips are formed, the carbide powder is pressed into a mold to form the tip. This tip is inserted directly and welded or brazed onto a tool shank. Thus, this is the art accepted way to form current design tools or bits.
Accordingly, it is an object of the present invention to provide the art with a cutting tool or bit which will reduce the time to drill holes into concrete, aggregate or the like material and improve the quality of the hole. The present invention has an improved cutting tip with a rake face which is slightly negative, zero or positive. The tip cutting angle, which is the angle between the rake face and clearance face, is smaller than current designs to provide better chiseling action. The debris recess of the present invention rapidly ejects debris from the tip into the helical flutes. A rake face on the cutting tools increases cutting action during rotation of the cutting tools in the hole.
Also, the present invention works the formed carbide tip, contrary to conventional teaching, to increase performance of the tip in drilling concrete, aggregate, masonry or the like material. The term xe2x80x9cworksxe2x80x9d means the tip is ground or otherwise machined to sharpen or form a sharpened cutting edge on the tool. Further, in a tool with a ball head the present invention defines a larger egress space than is conventionally taught. xe2x80x9cEgress spacexe2x80x9d is defined as the open volume through which debris may pass on its way from being created, to the flute of the bit to enable fast removal of debris.
In accordance with one aspect of the invention, a cutting tool comprises a longitudinally extending shank portion which defines a longitudinal axis and two ends. One end has a chucking part and the other end has a cutting head. A cutting edge on the cutting head includes at least one cutting portion. A rake surface is formed adjacent to at least one of the cutting portions. Also, a clearance face is formed adjacent to the at least one cutting portion opposite the rake face. An edge radius is formed between the rake face and the clearance face and has a radius from about 0.0005 to 0.001 inch. Likewise, a method of forming, by drilling or boring a hole in concrete, aggregate or the like material is disclosed using the above cutting tool. The cutting edge of the cutting tool is placed in contact with the concrete, aggregate or the like material. The cutting tool is rotated to form a hole in the material. Alternately, instead of rotating the tool, the tool may be impacted to chisel away the material to form the hole. Optionally both rotating and impacting may be conducted simultaneously.
In accordance with a second aspect of the invention, a cutting tool includes a longitudinally extending shank with a chucking end and a cutting head. A cutting edge is formed in the cutting head with at least one cutting edge portion. A rake surface is formed adjacent to at least one of the cutting portions with the rake face at an angle of from about xe2x88x9210xc2x0 to 10xc2x0. A method of forming, by boring or drilling, a hole in concrete, aggregate or the like material is disclosed using the above cutting tool. The cutting edge of the cutting tool is placed in contact with the material. The cutting tool is rotated to form a hole in the material. Alternatively, instead of rotating the tool, the tool may be impacted to chisel away the material to form the hole. Optionally both rotating and impacting may be conducted simultaneously.
In accordance with a third aspect of the invention, a cutting tool includes a shank portion with a chucking end and a cutting head. The head includes a cutting edge with at least one cutting edge portion. A rake surface is formed adjacent to at least one cutting edge portion. Additionally, a clearance surface is formed adjacent to the at least one cutting portion opposite the rake face. One or both the rake surface and clearance surface are worked to form a sharpened edge radius. A method of forming, by boring or drilling a hole in concrete, aggregate or the like material is disclosed using the cutting tool. The cutting edge of the cutting tool is placed in contact with the material. The cutting tool is rotated to form a hole in the material. Alternatively, instead of rotating the tool, the tool may be impacted to chisel away the material to form the hole. Optionally both rotating and impacting may be conducted simultaneously.
In accordance with a fourth aspect of the invention, a cutting tool comprises a longitudinal shank with a chucking part at one end and a cutting head at the other end. The cutting head includes a cutting edge with at least one cutting edge portion. A rake surface is formed adjacent to the at least one of the cutting edge portions. A primary egress surface is formed immediately adjacent the rake surface such that the rake surface and primary egress surface define a new egress path. A method of forming, by boring or drilling, a hole in concrete aggregate or the like material is disclosed using this cutting tool. The cutting edge of the cutting tool is placed in contact with the material. The cutting tool is rotated to form a hole in the material. Alternatively, instead of rotating the tool, the tool may be impacted to chisel away the material to form the hole. Optionally both rotating and impacting may be conducted simultaneously.
In accordance with a fifth aspect of the invention, a cutting tool comprises a longitudinally extending shank with a chucking part at one end and a cutting head at the other end. The cutting head includes a cutting edge with at least one cutting edge portion. A rake surface is formed adjacent to the at least one cutting edge portion. The rake surface includes a worked portion which extends from the cutting edge portion to define a length of relief. The ratio of the depth of the length of relief to tool diameter is in a range of about 0.10 to 0.32 inches per inch diameter of the tool. A method of forming, by boring or drilling, a hole into concrete, aggregate or the like material is disclosed using the above cutting tool. The cutting edge of the cutting tool is placed in contact with the aggregate. The cutting tool is rotated to form a hole in the material. Alternatively, instead of rotating the tool, the tool may be impacted to chisel away the material to form the hole. Optionally both rotating and impacting may be conducted simultaneously.
Additional objects and advantages of the invention will be apparent from the detailed description of the preferred embodiment, the appended claims and the accompanying drawings, or may be learned by practice of the invention.